Infection is a major concern associated with percutaneous and implant devices and an approach to such problem has recently focused on development of composite collagen-polymer matrices which can accommodate antimicrobial factors and which are compatible with the tissue. One of the problems is to enhance or impart tissue ingrowth properties to the non-degradable polymer matrix of such devices. In a collagen-polymer matrix, the collagen portion is naturally reabsorbed into the host tissues, therefore a viable environment for tissue interfacing with the device substrate (the polymer) is desired. However, if the epithelial tissues do not interface to the implant device, they will begin to propagate toward areas which may increase the chances of infection. For example, if a percutaneous device is an elastomeric cuff around a catheter, if the epithelial tissues do not adhere to the percutaneous cuff, they will begin to propagate down the catheter conduit, forming a sinus tract which may form a pathway for bacterial contamination and potentially serious infection.
It is therefore important to develop methods for creating controlled porosity for the elastomeric substrate which form a component of such percutaneous or implant devices, which improve or impart tissue ingrowth-inducing and tissue-interfacing properties and encourage epithelial growth into the device.
We have found that size, and in particular the shape, of pores on the surface of the elastomeric substrate are important in inducing tissue ingrowth properties. Imperfect pores, i.e. those which may form a circumferential mushroom on the surface surrounding the pore or which do not have smooth flat or slightly domed flat bottom surfaces, are undesirable. It is therefore important to devise a method to form the pores at the desired predetermined pore densities, sizes, and depths in an efficient manner which also achieve the desired pore shapes.
It is therefore an object of the present invention to provide a method for manufacturing a nonwoven, non-degradable tissue ingrowth-inducing, tissue-interfacing substrate with predetermined oriented sizes, pore densities and pore depths.
This and other objects of the invention will be apparent from the following description and from practice of the invention.